Your Family Physician

Introduction

Background

An understanding of panic disorder (PD) is important for emergency physicians because patients with panic disorder frequently present to the emergency department (ED) with various somatic complaints. As many as 70% of persons with panic disorder are unrecognized as having this condition, and few individuals with panic disorder are referred to mental health professionals.

Persons with panic disorder have a 4-fold higher risk of alcohol abuse and an 18-fold higher risk of suicide than the general population (although some studies suggest that panic disorder itself is not a risk factor for suicide in the absence of other risks, such as affective disorders, substance abuse, eating disorders, and personality disorders). Serious medical problems, such as asthma or cardiac dysrhythmia, or metabolic disturbances, such as hypoglycemia, hypoxia, and thyroid storm, can mimic panic attack.

Following exclusion of somatic disease and other psychiatric disorders, confirmation of the diagnosis with a brief mental status screening examination and initiation of appropriate treatment and referral is time- and cost-effective in these patients who have high rates of medical resource use.

See Medscape's Anxiety Disorders Resource Center for more information.

Pathophysiology

Panic disorder appears to be a genetically inherited neurochemical dysfunction that may involve autonomic imbalance; allelic polymorphism of the catechol-O-methyltransferase (COMT) gene; increased adenosine receptor function; increased cortisol; diminished benzodiazepine receptor function; and disturbances in serotonin, norepinephrine, gamma-aminobutyric acid, dopamine, cholecystokinin, and interleukin-1-beta. Some theorize that panic disorder may represent a state of chronic hyperventilation and carbon dioxide receptor hypersensitivity. Some epileptic patients have panic as a manifestation of their seizures.

Positron emission tomography (PET) scanning has demonstrated increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients with panic disorder. Magnetic resonance imaging (MRI) has demonstrated smaller temporal lobe volume despite normal hippocampal volume in these patients.

In experimental settings, symptoms can be elicited in people with panic disorder by hyperventilation, inhalation of carbon dioxide, caffeine consumption, or intravenous infusions of sodium lactate, cholecystokinin, isoproterenol, or flumazenil.

The cognitive theory regarding panic is that these patients have a heightened sensitivity to internal autonomic cues (eg, tachycardia).

Panic disorder is associated with depression, obsessive-compulsive disorder, restless leg syndrome, fatigue, specific phobias, social phobia, agoraphobia (ie, fear of being unsafe in public settings), irritable bowel syndrome, migraine, mitral valve prolapse, and alcohol and drug abuse. Individuals with panic disorder also have lower oxygen consumption and exercise tolerance than the general population. They also have reduced heart rate variability and increased QT variability on electrocardiography and may have a higher risk of cardiovascular disease and sudden death.

Frequency

United States

Panic disorder has an approximate 1-5% prevalence in the population.

International

Prevalence is similar to that in the United States.

Mortality/Morbidity

• Panic disorder can lead to a significant hindrance in lifestyle (many people with agoraphobia are unable to travel alone or be in crowds, malls, or on public transportation), unemployment, depression, substance abuse, and suicide.
• Panic disorder is present in 30% of patients with chest pain and normal findings on angiography, 5-40% of persons with asthma, 15% of patients with headache, 20% of patients with epilepsy, 8-15% of individuals in alcohol treatment programs, and 10% of patients in primary care settings.
• Panic disorder may be associated with a higher risk of cardiovascular disease and sudden death.
• A variant of panic disorder unrelated to fear (nonfearful panic disorder [NFPD]) is associated with high rates medical resource use (32-41% of patients with panic disorder seeking treatment for chest pain) and poor prognosis.

Sex

• Prevalence is higher in females than in males, with a female-to-male ratio of approximately 2:1.
• Panic is more common in women who have never been pregnant and during the postpartum period, but it is less common during pregnancy.

Age

• Although panic can occur in people at any age, the average age of onset, as with most anxiety disorders, is in the third decade of life, and it usually occurs between the ages of 18 and 45 years.
• Panic disorder has a bimodal age of onset, with patients with late-onset panic disorder having less mental health use, lower comorbidity and hypochondriasis, and better coping behavior.

Clinical

History

• Patients who experience panic attack report a spontaneous sudden onset of fear or discomfort, typically reaching a peak within 10 minutes.
• Attacks are associated with a constellation of systemic symptoms, including the following (4 or more of these are needed for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition [DSM-IV] criteria):
  • Palpitations, pounding heart, or accelerated heart rate
  • Sweating
  • Trembling or shaking
  • Shortness of breath or feeling of smothering
  • Choking sensation
  • Chest pain or discomfort
  • Nausea or abdominal distress
  • Feeling dizzy, unsteady, lightheaded, or faint
  • Derealization (ie, feeling of unreality) or depersonalization (ie, being detached from oneself)
  • Fear of losing control or going crazy
  • Fear of dying
  • Paresthesias (ie, numbness or tingling sensations)
  • Chills or hot flashes
• During the episode, patients have the urge to flee or escape and have a sense of impending doom (as though they are dying from a heart attack or suffocation).
• Other symptoms may include headache, cold hands, diarrhea, insomnia, fatigue, intrusive thoughts, and ruminations.
• Patients with panic disorder have recurring episodes of panic, with the fear of recurrent attack resulting in significant behavioral changes (eg, avoiding situations or locations) and worry about the implications of the attack or its consequences (eg, losing control, going crazy, dying).
• Panic disorder may result in changes in personality traits, characterized by the patient becoming more passive, dependent, or withdrawn.
• DSM-IV criteria include 4 or more attacks in a 4-week period or 1 or more attacks followed by at least 1 month of fear of another.
• Agoraphobia, present in 30% of persons with PD, establishes the diagnosis.
• Assess precipitating events, suicidal ideation or plan, phobias, agoraphobia, and obsessive-compulsive behavior.
• Exclude involvement of alcohol, illicit drugs (eg, cocaine, amphetamine, phencyclidine, amyl nitrate, lysergic acid diethylamide [LSD], yohimbine, 3,4-methylenedioxymethamphetamine [MDMA, ecstasy]), cannabis, and medications (eg, caffeine, theophylline, sympathomimetics, anticholinergics).
• Consider symptomatology of other medical disorders, which may manifest with anxiety as a primary symptom.
  • Angina and myocardial infarction (eg, dyspnea, chest pain, palpitations, diaphoresis)
  • Cardiac dysrhythmias (eg, palpitations, dyspnea, syncope)
  • Mitral valve prolapse
  • Pulmonary embolus (eg, dyspnea, hyperpnea, chest pain)
  • Asthma (eg, dyspnea, wheezing)
  • Hyperthyroidism (eg, palpitations, diaphoresis, tachycardia, heat intolerance)
  • Hypoglycemia
  • Pheochromocytoma (eg, headache, diaphoresis, hypertension)
  • Hypoparathyroidism (eg, muscle cramps, paresthesias)
  • Transient ischemic attacks (TIAs)
  • Seizure disorders
• Consider other mental illnesses that may result in panic attacks, including schizophrenia, manic disorder, depressive disorder, posttraumatic stress disorder, phobic disorders, and somatization disorder.
• Assess family history of panic or other psychiatric illness.

Physical

• The patient may have an anxious appearance.
• Tachycardia and tachypnea are common; blood pressure and temperature may be within the reference range.
• Cool clammy skin may be observed.
• Hyperventilation may be difficult to detect by observing breathing because respiratory rate and tidal volume may appear normal.
  • Patients may have frequent sighs or difficulty with breath holding.
  • Reproduction of symptoms with overbreathing is unreliable.
  • Chvostek sign, Trousseau sign, or overt carpopedal spasm may be present.
• Mental status screening is essential for diagnosis. Standardized examinations include the following:
  • Primary Care Evaluation of Mental Disorders (PRIME-MD)
  • Mobility Inventory for Agoraphobia (MIA)
  • The Agoraphobia Cognitions Questionnaire (ACA)
  • The Body Sensations Questionnaire (BSQ)
• The remaining examination findings are typically normal in panic disorder. However, remember that panic disorder is largely a diagnosis of exclusion, and attention should be focused on the exclusion of other disorders.

Causes

Triggers of panic can include the following:

• Injury (eg, accidents, surgery)
• Illness
• Interpersonal conflict or loss
• Use of cannabis (can be associated with panic attacks, perhaps because of breath-holding)
• Use of stimulants, such as caffeine, decongestants, cocaine, and sympathomimetics (eg, amphetamine, MDMA)
• Certain settings, such as stores and public transportation (especially in patients with agoraphobia)

Source : http://emedicine.medscape.com/article/806402-overview